[1.0.X] Fixed #9985 -- qs.values_list(...).values(...) was constructing incorrect SQL.

Backport of r9717 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@9718 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/query.py

@@ -667,6 +667,7 @@ class ValuesQuerySet(QuerySet):
         Called by the _clone() method after initializing the rest of the
         instance.
         """
+        self.query.clear_select_fields()
         self.extra_names = []
         if self._fields:
             if not self.query.extra_select:
@@ -691,7 +692,10 @@ class ValuesQuerySet(QuerySet):
         Cloning a ValuesQuerySet preserves the current fields.
         """
         c = super(ValuesQuerySet, self)._clone(klass, **kwargs)
-        c._fields = self._fields[:]
+        if not hasattr(c, '_fields'):
+            # Only clone self._fields if _fields wasn't passed into the cloning
+            # call directly.
+            c._fields = self._fields[:]
         c.field_names = self.field_names
         c.extra_names = self.extra_names
         if setup and hasattr(c, '_setup_query'):

django/db/models/sql/query.py

@@ -1535,6 +1535,15 @@ class BaseQuery(object):
         """
         return not (self.low_mark or self.high_mark)
 
+    def clear_select_fields(self):
+        """
+        Clears the list of fields to select (but not extra_select columns).
+        Some queryset types completely replace any existing list of select
+        columns.
+        """
+        self.select = []
+        self.select_fields = []
+
     def add_fields(self, field_names, allow_m2m=True):
         """
         Adds the given (model) fields to the select set. The field names are

tests/regressiontests/queries/models.py

@@ -1020,6 +1020,10 @@ cases).
 # optimise the inner query without losing results.
 >>> Annotation.objects.exclude(tag__children__name="t2")
 [<Annotation: a2>]
+
+Bug #9985 -- qs.values_list(...).values(...) combinations should work.
+>>> Note.objects.values_list("note", flat=True).values("id").order_by("id")
+[{'id': 1}, {'id': 2}, {'id': 3}]
 """}
 
 # In Python 2.3 and the Python 2.6 beta releases, exceptions raised in __len__